Hydroxy-dialkylbenzylthioalkanoates

ABSTRACT

ARE USED AS STABILIZERS FOR ORGANIC COMPOSITIONS. IN THE FORMULAE: N IS AN INTEGER FROM 1 TO 4 R1 AND R2 ARE ALKYL R3 FOR N=1 IS A MEMBER OF THE GROUP CONSISTING OF THIOETHER, ETHER, AND ALKYL RADICALS AND FOR N=2-4 AN ALKYLENE GROUP, AND X IS ALKYLENE.   ((2-(HO-),3-R1,5-R2-PHENYL)-CH2-S-X-COO)N-R3   ((3-R1,4-(HO-),5-R2-PHENYL)-CH2-S-X-COO)N-R3 AND   COMPOUNDS OF THE FORMULA

United States Patent 3,637,802 HYDROXY-DIALKYLBENZYLTHIOALKANOATES Heinz Eggensperger, Gadernheim over Bensheim, Volker Franzen, Heidelberg, Horst Muller, Furth-Odenwald, and Hans Stephan, Bensheim, Bergstrasse, Germany, assignors to Deutsche Advance Produktion G.m.b.H., Lantern am Odenwald, Germany N0 Drawing. Filed Aug. 17, 1967, Ser. No. 661,213 Claims priority, application Germany, Aug. 18, 1966,

D 50,874 Int. Cl. C07c 149/40 US. Cl. 260-470 7 Claims ABSTRACT OF THE DISCLOSURE Compounds of the formula are used as stabilizers for organic compositions. In the formulae:

n is an integer from 1 to 4 R and R are alkyl R for n=1 is a member of the group consisting of thioether, ether, and alkyl radicals and for n=24 an alkylene group, and

X is alkylene.

This invention relates to novel mercaptocarboxylic acid esters and to organic compounds stabilized therewith.

The new mercapto carboxylic acid esters are (hydroxydialkyl-benzyl) mercapto alkane-carboxylic acid esters of the formulae wherein n is an integer from 1 to 4,

R and R are the same or different linear or branched alkyl groups having preferably 1 to 6 C atoms, R is a linear, branched or cyclic thioether, ether, or alkyl group (if n=l) or an alkylene group (if n=24), containing 1-20 C atoms, whereby said groups may be substituted, and X is a linear or branched lower alkylene group.

The compounds of the invention are useful as stabilizers against photochemical, thermochemical, and oxi- 3,637,802 Patented Jan. 25, 1972 wherein R for nl=1 is a linear, branched, or cyclic alkyl, thioether, or ether group, which may be substituted, and which contains a total of 8 to 20 C atoms; for n=2-4 R is a linear, branched or cyclic alkylene, thioether, or ether group which may be substituted and which contains a total of 2-10 C-atoms.

Those compounds of this group in which n=1 and R contains 12 or more carbon atoms, are physiologically harmless and therefore suitable for the stabilization of edible fats or oils and for food wrappings. (4-hydroxy- 2,6-dimethyl-benzyl) thioglycolic acid stearyl ester (R =C H e.g., has shown to be completely untoxic in rat feeding tests.

Generally, the stabilizers of the invention are used in amounts of 0.001 to 10 percent, preferred 0.05 to 5%, calculated on the total weight of the material to be stabilized.

The new compounds of the invention can be prepared by various methods. We prefer the following procedures:

(1) The reaction of Mannich bases of the general formula wherein R and R have the significance given above, and R is a preferably lower alkyl group, with mercaptoacid esters in a dry inert organic solvent such as toluene, or with an alcohol corresponding to the R residue, in the presence of a catalytic amount of a base, preferably an alkali metal or alkaline earth metal alcoholate, or

(2) the reaction of the respective dialkyl phenols with mercaptoacids and formaldehyde, or formaldehyde developing substances, in an inert solvent or lower alcohol in the presence of a base, preferably an alkali metal or alkaline earth metal alcoholate, and esterification of the thus obtained acids.

Said preparation methods furnish the new compounds in yields of 70 to percent.

Some examples of compounds corresponding to Formula Ia are given in Table I, and examples of compounds corresponding to Formula Ib are given in Table II.

TABLE I Melting point Stabilizer n R: C C.) numeral 1 CH41 54-56 1 -C11Ha1 52-53 I 1 -oo-o,m

1 CioH2t II 1 CHzCH2OCtH 1 CH2CH2SC2H5 III 2 (CH2)4 75 IV -CH2CCH2 GII; CH3 -CHz- 4 CH2- --CH2CCH2 Isopropyl 1s0propyl CH2- 1 -C1 Ha1 -47 V CH Tert-butyl oH1- 1 C1BI{31 444e Tert-butyl d0 CI-Iz 1 CH3 57-50 Do .d0 CH2 1 .D0 d0 CH2 1 -51 Do d0 -CH2CH2 1 CisHs1 38-41 Do .do CH 1 C1sH:1

1 Liquid. 2 Viscous resin.

TABLE II 35 Stabilizer I and V see Table I. In the films stabilized with said stabilizers, the oxidative degradation started later Melting point stabilizer than in the films stabihzed with the known stabilizers. R1 Rz X 17. R3 C.) Numeral EXAMPLE 2 CH3 CH2 1 CiaHa7 66-68 L- W 1 C18H31 6H9 Stabilization of an ABS resin tert-buty do 2- 1 -C1sH31 56-58 1 OH3 Three mixtures (Table IV) were prepared, each from Our novel stabilizers have an improved stabilizing effect when compared with known purely organic stabilizers such as the mixtures of alkylated phenols (German DAS 1,035,137) thiobis-phenols, and w-(hydroxy-alkyl-phenyl)- alkane carboxylic acid esters (German DAS 1,201,349); they are also more effective than the thiobisphenols which have been considered to belong to the best stabilizers of the type here involved.

The following examples illustrating the stabilizing effect of the new stabilizers are merely illustrative and are not intended to limit the invention to the specific materials and details disclosed.

EXAMPLE 1 Stabilization of polypropylene To 100 parts each of unstabilized polypropylene powder, the stabilizers listed in Table II were added. All mixtures were treated for 10 minutes at 180 C. on a laboratory roll mill, and the obtained films were-pressed at 200 atm. and at a temperature of 210 C. From the obtained 1 mm. thick sheets, 5 strips were cut out and subjected by storage in a drying cabinet at 150 C. to an accelerated ageing; the time was determined after which an oxidative decomposition could be observed by the brittleness test.

TABLE III Stabilizer Oxidative degradation (Parts by weight): after days (Brittleness test) 0.5 L 45 0.2 L+O.3 DLTDP 72 0.5 M G5 0.5 Stabilizer I 100 0.5 Stabilizer V 110 Stabilizer L:4,4-tl1iobis(G-tert.bl1tyl-1n-c1'esol) Stabilizer M [3- (JLS-(li-tvrthutylA-hydroxy-pltenyl) -p1'opi0nie acid steal-- ate DL'iP:dilaurylthiodiporopionttte.

TABLE IV Brlttleness starting after Stabilizer (parts by Weight) Color after 30 days (days) 0.25 2,5-di-tert.butyl-p-eresol 0.25 2,6 dirnethylphenol Brown 47 0.5 Stabilizer L .do 40 0.5 Stabilizer I Light brown 55 The stabilizer of the invention shows distinctly a better effect.

EXAMPLE 3 Stabilization of polyamide (condensation products of dicarboxylic acids and diamines) The four mixtures listed in Table V were prepared each from parts of polyamide and 1 part of stabilizer and extruded at 250 C. to sheets from which samples were cut and subjected to accelerated ageing in a drying cabinet at C.

The stabilizing efiect was determined by the brittleness test and the color of the samples.

Particularly in combination with aryl phosphites, the stabilizers of the invention show a superior stabilizing effect.

EXAMPLE 4 Stabilization of mineral oil (Gardner color) number 3-4, viscosity 144 cps. at 20 C.

100 g. each of a mineral oil were mixed with the stabilizers listed in Table VI, and 5 liters of oxygen were passed through the oil for 90 minutes at 190 C. The oxidative degradation of the oil was determined by the viscosity increase.

TABLE VI Stabilizer: Viscosity, cps. at 20 C. 0.05 g. 2,4,6-tri-tert. butyl phenol, 0.05 g. 2,4-

dimethylphenol 188 0.1 g. stabilizer M 192 0.1 g. stabilizer VI 165 0.05 g. stabilizer III, 0.05 g. tris-nonylphenylphosphite 160 The stabilizers of the invention (III and VI) retard best the oxidative degradation of the oil. As shown by the table, their addition resulted in the smallest viscosity increase.

EXAMPLE 5 Stabilization of vegetable oils and plasticizers The same stabilizers as employed in Table V were used in a similar manner for a vegetable oil (olive oil) and a plasticizer (dioctylphthalate). The results were similar to those obtained with the mineral oil.

We claim:

1. As new compounds (hydroxydialkyl-benzyl) mercapto alkane carboxylic acid esters of the formulae:

wherein n is an integer from 1 to 4, R and R are alkyl having 1 to 6 carbons, R for n:1 is a member of the group consisting of alkyloxyalkyl, alkylthioalkyl and alkyl radicals having up to 20 carbon atoms and R for 12:2 is alkdiyl having up to 10 carbon atoms, R for n:3 is alktriyl having up to 10 carbon atoms, and R for 11:4 is alktetrayl having up to 10 carbon atoms, and X is a lower alkylene.

2. A compound of claim 1 corresponding to the for wherein n is 1, 2 or 4, R and R are selected from the group consisting of methyl, isopropyl and tertiary butyl, R for n:1 is selected from the group consisting of methyl, octyl, decyl, octadecyl, eicosyl, butoxyethyl, ethylthioethyl, benzyl and cyclohexyl, for 11:2, R is selected from the group consisting of tetramethylene and 2,2-diethylpropylene, and for 11:4, R is and X is selected from the group consisting of methylene, ethylene and methylmethylene.

3. A compound of claim 1 corresponding to the formula wherein R and R are selected from the group consisting of methyl and tertiary butyl, R is an alkyl having 1 to 18 carbons and X is methylene.

4. The compound of claim 2 wherein R and R are methyl, n is 1, and R is selected from the group consisting of octyl, decyl, octadecyl and ethylthioethyl and X is methylene.

5. The compound of claim 2 wherein R and R are isopropyl, n is 1, R is octadecyl and X is methylene.

6. The compound of claim 2 wherein R and R are methyl, n is 2, R is tetramethylene and X is methylene.

7. The compound of claim 3 wherein R is methyl, R is tertiary butyl, R is octadecyl and X is methylene.

References Cited UNITED STATES PATENTS 3,546,272 12/1970 Braus et al 260-470 3,504,012 5/1970 Braus et al. 260-470 3,285,855 11/1966 Dexter 252-57 3,249,632 4/1966 Peterson 260-473 3,144,422 8/1964 Homberg 260-23 LORRAINE A. WEINBERGER, Primary Examiner E. J. GLEIMAN, Assistant Examiner U.S. Cl. X.R. 

